Gui: Scene inspector improvements (#18781)

* Improve naming for root scene graph switch/separator nodes.

* Improve scene graph inspector.

This commit improves the scene graph inspector by improving the UI
layout and displaying information in a more human-readable way.

Instead of having a main generic string column for all node-specific
data, introduce specific columns for node name, memory address and data.

Better visualization was also added for `SoDrawStyle`, `SoPickStyle`
and `SoCoordinate3` node types.

src/Gui/ViewProvider.cpp

@@ -107,6 +107,7 @@ ViewProvider::ViewProvider()
     pcRoot->ref();
     pcModeSwitch = new SoSwitch();
     pcModeSwitch->ref();
+    pcModeSwitch->setName("ModeSwitch");
     pcTransform  = new SoFCTransform();
     pcTransform->ref();
     pcRoot->addChild(pcTransform);